Optical amplification apparatus

Abstract

An optical amplification apparatus for adjusting optical power of wavelength-multiplexed signal light at respective wavelengths and for adjusting the optical output power at the respective wavelengths and a deviation of the optical output power between the wavelengths. An optical power adjusting unit for receiving inputted light having signal light at a plurality of different wavelengths ( lambda 1, lambda 2, lambda 3, . . . lambda N) multiplexed thereon, amplifying or attenuating light at least one wavelength included in the received light independently of light at different wavelengths from the wavelength of the light, is provided before or after an optical amplifier unit for amplifying the light having the signal light at the plurality of different wavelengths multiplexed thereon. Further, a control unit is provided for controlling the gain of amplification or attenuation performed by the optical power adjusting unit and the gain of amplification performed by the optical amplifier unit, respectively.

I claim: 
     
       1. An optical transmission system comprising: an optical transmission path;   a receiver for receiving light signals propagated through said optical transmission path; and   a transmitter for producing a multiplexed light signal having light signals at a plurality of different wavelengths,   wherein said transmitter comprises: a plurality of optical transmitters for outputting light signals, each having a peculiar wavelength;   at least one optical gain adjusting unit for receiving at least one light signal from at least one of said optical transmitters, for adjusting an optical power of said at least one light signal, and for outputting at least one adjusted light signal;   an optical coupler for multiplexing said at least one adjusted light signal together with other light signals from said plurality of optical transmitters to form a multiplexed light signal; and   an optical amplifier for amplifying said multiplexed light signal.     
     
     
       2. An optical transmission system comprising: a transmitter for transmitting a multiplexed light signal having light signals at a plurality of different wavelengths;   a first optical transmission path through which said multiplexed light signal transmitted by said transmitter propagates;   a second optical transmission path;   an optical power adjuster coupled to receive said multiplexed light signal for amplifying or attenuating a selected light signal at at least one wavelength included in said multiplexed light signal independently of remaining light signals of said multiplexed light signal;   an optical amplifier for amplifying said selected light at the at least one wavelength amplified or attenuated by said optical power adjuster, and for relaying an amplified multiplexed light signal to said second transmission path;   a controller for controlling a gain of amplification or attenuation performed by said optical power adjuster and a gain of amplification performed by said optical amplifier, respectively; and   a receiver for receiving the multiplexed light signal having propagated through said second optical transmission path.   
     
     
       3. An optical transmission system comprising: a transmitter for transmitting a multiplexed light signal having light signals at a plurality of different wavelengths;   a first optical transmission path through which said multiplexed light signal transmitted by said transmitter propagates;   a second optical transmission path;   an optical amplifier for amplifying said multiplexed light signal;   an optical power adjuster coupled to receive said multiplexed light signal amplified by said optical amplifier for amplifying or attenuating light at at least one wavelength included in said multiplexed light signal independently of remaining light signals of said multiplexed light signal, and for relaying the amplified multiplexed light signal to said second transmission path;   a controller for controlling a gain of amplification performed by said optical amplifier and a gain of amplification or attenuation performed by said optical power adjuster, respectively; and   a receiver for receiving the multiplexed light signal having propagated through said second optical transmission path.   
     
     
       4. An optical transmission system comprising: a transmitter for transmitting a multiplexed light signal having light signals at a plurality of different wavelengths;   an optical transmission path through which said multiplexed light signal transmitted by said transmitter propagates;   an optical power adjuster coupled to receive said multiplexed light signal for amplifying or attenuating a selected light signal at at least one wavelength included in said multiplexed light signal independently of remaining light signals of said multiplexed light signal;   an optical amplifier for amplifying said selected light signal at the at least one wavelength amplified or attenuated by said optical power adjuster;   a controller for controlling a gain of amplification or attenuation performed by said optical power adjuster and a gain of amplification performed by said optical amplifier, respectively; and   a receiver for receiving said multiplexed light signal amplified by said optical amplifier.   
     
     
       5. An optical transmission system comprising: a transmitter for transmitting a multiplexed light signal having light signals at a plurality of different wavelengths;   an optical transmission path through which the multiplexed light signal transmitted by said transmitter propagates;   an optical amplifier for amplifying said multiplexed light signal;   optical power adjuster coupled to receive said multiplexed light signal amplified by said optical amplifier for amplifying or attenuating light at at least one wavelength included in said multiplexed light signal independently of remaining light signals of said multiplexed light signal;   a controller for controlling a gain of amplification performed by said optical amplifier and a gain of amplification or attenuation performed by said optical power adjuster, respectively; and   a receiver for receiving the multiplexed light signal amplified by said optical power adjuster.   
     
     
       6. An optical transmission system comprising: an optical booster amplifier for multiplexing a plurality of light signals each having a peculiar wavelength and for amplifying the multiplexed light signals, said optical booster amplifier comprising: a plurality of input fibers;   at least one optical gain adjusting unit receiving at least one light signal from an input fiber selected from said plurality of input fibers, adjusting an optical power of said at least one light signal, and outputting at least one adjusted light signal;   an optical coupler multiplexing said at least one adjusted light signal together with other light signals from said plurality of input fibers to form a multiplexed light signal; and   an optical amplifier amplifying said multiplexed light signal;     an optical transmission path through which said multiplexed light signal from said optical amplifier propagates; and   a receiver for receiving said multiplexed light signal from said optical transmission path.   
     
     
       7. An optical transmission system comprising: an optical pre-amplifier for amplifying a wavelength multiplexed light signal and for demultiplexing said wavelength multiplexed light signal to a plurality of wavelengths, said optical pre-amplifier comprising: an optical amplifier amplifying said wavelength multiplexed light signal;   an optical coupler receiving an amplified said wavelength multiplexed light signal, and dividing the amplified said wavelength multiplexed light signal to a plurality of multiplexed light signals;   a plurality of optical band-pass filters each receiving a divided multiplexed light signal from said optical coupler, and each passing a peculiar band pass wavelength to output a demultiplexed light signal;   at least one optical gain adjusting unit receiving said demultiplexed light signal from one of the optical band pass filters, adjusting an optical power of said demultiplexed light signal, and outputting an adjusted light signal; and   a controller for controlling gain performed by said at least one optical gain adjusting unit such that said at least one optical gain adjusting unit provides an attenuable low gain optical amplifying function;     an optical transmission path through which said multiplexed light signal from said optical gain adjusting unit propagates; and   a receiver for receiving said multiplexed light signal from said optical transmission path.   
     
     
       8. An optical transmission system comprising: an optical pre-amplifier for amplifying a wavelength multiplexed light signal and for demultiplexing said wavelength multiplexed light signal to a plurality of light signals, said optical pre-amplifier comprising: an optical amplifier amplifying said wavelength multiplexed light signal;   an optical wavelength demultiplexer receiving and demultiplexing the amplified said wavelength multiplexed light signal to a plurality of demultiplexed light signals each having a perpendicular wavelength;   at least one optical gain adjusting unit receiving a demultiplexed light signal from the optical wavelength demultiplexer, adjusting an optical power of said demultiplexed light signal, and outputting an adjusted light signal; and   a controller for controlling gain performed by said at least one optical gain adjusting unit such that said at least one optical gain adjusting unit provides an attenuable low gain optical amplifying function;     an optical transmission path through which said multiplexed light signal from said optical gain adjusting unit propagates; and   a receiver for receiving said multiplexed light signal from said optical transmission path.   
     
     
       9. An optical transmission system comprising: a first optical transmission path through which a wavelength multiplexed light signal propagates;   a second optical transmission path through which a repeated wavelength multiplexed light signal propagates;   an optical repeating apparatus for repeating said wavelength multiplexed light signal while applying selective gain adjustment thereto, said optical repeating apparatus comprising: a wavelength demultiplexer receiving and demultiplexing an input said wavelength multiplexed light signal to a plurality of demultiplexed light signals each having a peculiar wavelength;   at least one optical gain adjusting unit receiving a demultiplexed light signal from said wavelength demultiplexer, adjusting an optical power of said demultiplexed light signal, and outputting an adjusted light signal;   an optical multiplexer receiving and multiplexing both said adjusted light signal and said demultiplexed light signals which do not pass through said optical gain adjusting unit, and outputting said repeated wavelength multiplexed light signal;   an optical amplifier amplifying said repeated wavelength multiplexed light signal and outputting the amplified said repeated wavelength multiplexed light signal to said second optical transmission path; and   a controller for controlling gain adjustment provided by said optical gain adjusting unit such that said at least one optical gain adjusting unit provides an attenuable low gain optical amplifying function.     
     
     
       10. An optical transmission system comprising: a first optical transmission path through which a wavelength multiplexed light signal propagates;   a second optical transmission path through which a repeated wavelength multiplexed light signal propagates;   an optical repeating apparatus for repeating a wavelength multiplexed light signal while applying selective gain adjustment thereto, said optical repeating apparatus comprising: an optical amplifier for amplifying an input said wavelength multiplexed light signal;   a wavelength demultiplexer receiving and demultiplexing the amplified said input wavelength multiplexed light signal to a plurality of demultiplexed light signals each having a each peculiar wavelength;   at least one optical gain adjusting unit receiving a demultiplexed light signal from said wavelength demultiplexer, adjusting an optical power of said demultiplexed light signal, and outputting an adjusted light signal;   an optical multiplexer receiving and multiplexing both said adjusted light signal and said demultiplexed light signals which do not pass through said optical gain adjusting unit, and outputting a repeated wavelength multiplexed light signal to said second optical transmission path; and   a controller for controlling gain adjustment provided by said optical gain adjusting unit such that said at least one optical gain adjusting unit provides an attenuable low gain optical amplifying function.     
     
     
       11. An optical transmission system as claimed in claim 10, wherein said optical repeating apparatus further comprising: a coupler extracting at least one of a portion of the input said wavelength multiplexed light signal and a portion of said repeated wavelength multiplexed light signal;   a power monitor receiving the at least one of the portion of said input wavelength multiplexed light signal and the portion of said repeated wavelength multiplexed light signal, and monitoring a power level of the same; and   said controller receiving said power level from said power monitor and controlling gain adjustment in relation to said power level.   
     
     
       12. An optical transmission system as claimed in claim 11, wherein said optical repeating apparatus further comprising: a coupler extracting at least one of a portion of the input said wavelength multiplexed light signal and a portion of said repeated wavelength multiplexed light signal;   a power monitor receiving the at least one of the portion of said input wavelength multiplexed light signal and the portion of said repeated wavelength multiplexed light signal, and monitoring a power level of the same; and   said controller receiving said power level from said power monitor and controlling gain adjustment in relation to said power level.   
     
     
       13. An optical transmission system comprising: an optical booster amplifier for multiplexing a plurality of light signals each having a peculiar wavelength and for amplifying the multiplexed light signals, said optical booster amplifier comprising: a plurality of input fibers;   at least one optical gain adjusting unit receiving at least one light signal from an input fiber selected from said plurality of input fibers, adjusting an optical power of said at least one light signal via amplification, and outputting at least one adjusted light signal;   a controller for controlling gain performed by said at least one optical gain adjusting unit such that said at least one optical gain adjusting unit provides an attenuable low gain optical amplifying function;   an optical coupler multiplexing said at least one adjusted light signal together with other light signals from said plurality of input fibers to form a multiplexed light signal; and     an optical transmission path through which said multiplexed light signal from said optical coupler propagates; and   a receiver for receiving said multiplexed light signal from said optical transmission path.   
     
     
       14. An optical transmission system comprising: an optical pre-amplifier for amplifying a wavelength multiplexed light signal and for demultiplexing said wavelength multiplexed light signal to a plurality of wavelengths, said optical pre-amplifier comprising: an optical coupler receiving said wavelength multiplexed light signal, and dividing said wavelength multiplexed light signal to a plurality of multiplexed light signals;   a plurality of optical band-pass filters each receiving a divided multiplexed light signal from said optical coupler, and each passing a peculiar band pass wavelength to output a demultiplexed light signal; and   at least one optical gain adjusting unit receiving said demultiplexed light signal from one of the optical band pass filters, adjusting an optical power of said demultiplexed light signal via amplification, and outputting an adjusted light signal; and   a controller for controlling gain performed by said at least one optical gain adjusting unit such that said at least one optical gain adjusting unit provides an attenuable low gain optical amplifying function;     an optical transmission path through which said multiplexed light signal from said optical gain adjusting unit propagates; and   a receiver for receiving said multiplexed light signal from said optical transmission path.   
     
     
       15. An optical transmission system comprising: an optical pre-amplifier for amplifying a wavelength multiplexed light signal and for demultiplexing said wavelength multiplexed light signal to a plurality of light signals, said optical pre-amplifier comprising: an optical wavelength demultiplexer receiving and demultiplexing said wavelength multiplexed light signal to a plurality of demultiplexed light signals each having a perpendicular wavelength;   at least one optical gain adjusting unit receiving a demultiplexed light signal from the optical wavelength demultiplexer, adjusting an optical power of said demultiplexed light signal via amplification, and outputting an adjusted light signal; and   a controller for controlling gain performed by said at least one optical gain adjusting unit such that said at least one optical gain adjusting unit provides an attenuable low gain optical amplifying function;     an optical transmission path through which said multiplexed light signal from said optical gain adjusting unit propagates; and   a receiver for receiving said multiplexed light signal from said optical transmission path.   
     
     
       16. An optical transmission system comprising: a first optical transmission path through which a wavelength multiplexed light signal propagates;   a second optical transmission path through which a repeated wavelength multiplexed light signal propagates;   an optical repeating apparatus for repeating said wavelength multiplexed light signal while applying selective gain adjustment thereto, said optical repeating apparatus comprising: a wavelength demultiplexer receiving and demultiplexing an input wavelength multiplexed light signal to a plurality of demultiplexed light signals each having a peculiar wavelength;   at least one optical gain adjusting unit receiving a demultiplexed light signal from said wavelength demultiplexer, adjusting an optical power of said demultiplexed light signal via amplification, and outputting an adjusted light signal;   an optical multiplexer receiving and multiplexing both said adjusted light signal and said demultiplexed light signals which do not pass through said optical gain adjusting unit, and outputting a repeated wavelength multiplexed light signal to said second optical transmission path; and   a controller for controlling gain performed by said at least one optical gain adjusting unit such that said at least one optical gain adjusting unit provides an attenuable low gain optical amplifying function;   a controller for controlling gain adjustment provided by said optical gain adjusting unit.     
     
     
       17. An optical transmission system comprising: a first optical transmission path through which a wavelength multiplexed light signal propagates;   a second optical transmission path through which a repeated wavelength multiplexed light signal propagates;   an optical repeating apparatus for repeating a wavelength multiplexed light signal while applying selective gain adjustment thereto, said optical repeating apparatus comprising: a wavelength demultiplexer receiving and demultiplexing an input said wavelength multiplexed light signal to a plurality of demultiplexed light signals each having a each peculiar wavelength;   at least one optical gain adjusting unit receiving a demultiplexed light signal from said wavelength demultiplexer, adjusting an optical power of said demultiplexed light signal via amplification, and outputting an adjusted light signal;   an optical multiplexer receiving and multiplexing both said adjusted light signal and said demultiplexed light signals which do not pass through said optical gain adjusting unit, and outputting a repeated wavelength multiplexed light signal to said second optical transmission path; and   a controller for controlling gain adjustment provided by said optical gain adjusting unit.